Appointment scheduling with unscheduled arrivals and reprioritization

Inspired by the real life problem of a radiology department in a Dutch hospital, we study the problem of scheduling appointments, taking into account unscheduled arrivals and reprioritization. The radiology department offers CT diagnostics to both scheduled and unscheduled patients. Of these unscheduled patients, some must be seen immediately, while others may wait for some time. Herein a trade-off is sought between acceptable waiting times for appointment patients and unscheduled patients’ lateness. In this paper we use a discrete event simulation model to determine the performance of a given appointment schedule in terms of waiting time and lateness. Also we propose a constructive and local search heuristic that embeds this model and optimizes the schedule. For smaller instances, we verify the simulation model as well as compare our search heuristics’ performance with optimal schedules obtained using a Markov reward process. In addition we present computational results from the case study in the Dutch hospital. These results show that a considerable decrease of waiting time is possible for scheduled patients, while still treating unscheduled patients on time

Fielding incognito standardised patients as 'known' patients in a controlled trial in general practice

Incognito standardised patients (SPs) have only been used to represent new patients so far. The few trials with incognito SPs provide little detail on the method used for fielding them. To establish the feasibility of introducing SPs as 'known' patients (i.e. patients who have previously visited the practice) into practices, to indicate the required practice preparations, and to describe the various aspects of using SPs in a pretest/post-test design. We used incognito SPs as known patients in a controlled trial to assess the practice behaviour of 49 trainees. The SPs received a 2-day training in role playing and completing checklists. We compiled comprehensive practice information folders of each practice to be visited. Real personal data and faked medical data of SPs were inserted in the filing system of each practice to be visited. Apart from SP roles with slightly different reasons-for-encounter and different SPs, the same training protocol, checklists and practice information folders were used in the post-test. The SPs carried out 287 visits in 50 practices. All practices prepared the patient records for the SP visits in a fairly authentic practice style. Trainees detected the SP in 74 visits. The main reasons for detection were imperfections in patient records and aspects of SP roles or role playing. Fielding incognito SP visits as known patients was feasible but labour-intensive. Preparing the SP patient records and familiarising SPs with the interior of practices represented new elements in the use of SPs. The pretest/post-test format made their use more efficient instead of complicating i

Evaluating theAge-BasedRecommendations forLong-Term Follow-Upin Breast Cancer

BACKGROUND: After 5 years of annual follow-up following breast cancer, Dutch guidelines are age based: annual follow-up for women 75 years. We determined how the risk of recurrence corresponds to these consensus-based recommendations and to the risk of primary breast cancer in the general screening population. SUBJECTS, MATERIALS, AND METHODS: Women with early-stage breast cancer in 2003/2005 were selected from the Netherlands Cancer Registry (n = 18,568). Cumulative incidence functions were estimated for follow-up years 5-10 for locoregional recurrences (LRRs) and second primary tumors (SPs). Risks were compared with the screening population without history of breast cancer. Alternative cutoffs for age were determined by log-rank tests. RESULTS: The cumulative risk for LRR/SP was lower in women  69 revealed better risk differentiation and would provide more risk-based schedules. Still, other factors, including systemic treatments, had an even greater impact on recurrence risks. CONCLUSION: The current consensus-based recommendations use suboptimal age cutoffs. The proposed alternative cutoffs will lead to a more balanced risk-based follow-up and thereby more efficient allocation of resources. However, more factors should be taken into account for truly individualizing follow-up based on risk for recurrence. IMPLICATIONS FOR PRACTICE: The current age-based recommendations for breast cancer follow-up after 5 years are suboptimal and do not reflect the actual risk of recurrent disease. This results in situations in which women with higher risks actually receive less follow-up than those with a lower risk of recurrence. Alternative cutoffs could be a start toward risk-based follow-up and thereby more efficient allocation of resources. However, age, or any single risk factor, is not able to capture the risk differences and therefore is not sufficient for determining follow-up. More risk factors should be taken into account for truly individualizing follow-up based on the risk for recurrence

ORchestra: an online reference database of OR/MS literature in health care

Health care services, Operations Research and Management Science (OR/MS), Reference database, Bibliography,

Early changes in rat hearts with developing pulmonary arterial hypertension can be detected with three-dimensional electrocardiography

The study aim was to assess three-dimensional electrocardiogram (ECG) changes during development of pulmonary arterial hypertension (PAH). PAH was induced in male Wistar rats (n = 23) using monocrotaline (MCT; 40 mg/kg sc). Untreated healthy rats served as controls (n = 5). ECGs were recorded with an orthogonal three-lead system on days 0, 14, and 25 and analyzed with dedicated computer software. In addition, left ventricular (LV)-to-right ventricular (RV) fractional shortening ratio was determined using echocardiography. Invasively measured RV systolic pressure was 49 (SD 10) mmHg on day 14 and 64 (SD 10) mmHg on day 25 vs. 25 (SD 2) mmHg in controls (both P < 0.001). Baseline ECGs of controls and MCT rats were similar, and ECGs of controls did not change over time. In MCT rats, ECG changes were already present on day 14 but more explicit on day 25: increased RV electromotive forces decreased mean QRS-vector magnitude and changed QRS-axis orientation. Important changes in action potential duration distribution and repolarization sequence were reflected by a decreased spatial ventricular gradient magnitude and increased QRS-T spatial angle. On day 25, LV-to-RV fractional shortening ratio was increased, and RV hypertrophy was found, but not on day 14. In conclusion, developing PAH is characterized by early ECG changes preceding RV hypertrophy, whereas severe PAH is marked by profound ECG changes associated with anatomical and functional changes in the RV. Three-dimensional ECG analysis appears to be very sensitive to early changes in RV afterload